Total testing process and test ordering

The total testing process (TTP) is a multistep process that begins and ends with the needs of the patient. The total testing process consists of three key components or phases as shown in Figure 1.1 and is presented here in briefly with reference to appropriate utilisation of clinical microbiology tests. These phases are pre-analytical, analytical and post-analytical phase.

Identifying the many steps in the TTP and planning and using an interdisciplinary team to begin a coordinated effort will improve the process and offer optimal patient care. The TTP is one of the systems used in applying quality management approaches to the clinical laboratory (Barr and Silver 1994, Schumacher and Barr 1998). The TTP refers to the sequence of eleven steps of laboratory testing, outlined in Figure 1.1, beginning with a clinical question prompted by the patient-clinical encounter and concluding with the impact of the test result on patient care.

Clinical microbiology testing, like other clinical laboratory testing, is a highly complex process. Therefore, TTP describes the full sequence of laboratory testing activities, which, when applied to the analysis and interpretation of clinical microbiology specimens, leads to decision that influence patient outcome resulting from test results.

The testing cycle, commonly called the TTP was well described several years ago by George D. Lundberg, who pictured it as a “brain-to-brain” (Lundberg 1999). The starting point for a microbiology test, a question made by the physician to the laboratory, can concern diagnostic, prognostic and monitoring processes, and/or health maintenance and promotion. The end result of the testing cycle is patient outcome and the effectiveness of laboratory information in improving medical and economical outcomes. In this cyclical process, the laboratory test is ordered, the patient identified, and the specimen collected, transported and prepared for analysis and process. After the specimen has been analysed, the results are interpreted and reported to the physician or whoever ordered the tests. The action finally taken is based on the interpretation of the test results.

Traditionally, microbiology laboratories have focused their attention on quality control methods and quality assessment programmes dealing with analytical aspects. However, a growing body of evidence accumulated in recent decades demonstrates that quality in clinical laboratories cannot be assured by simply focussing on purely analytical aspects (Plebani and Carraro 1997). A study review of errors in laboratory medicine concluded that in the delivery of laboratory testing, mistakes occur more frequently (pre-analytical phase) and after, the test has been performed (Bonini et al. 2002).

Many of the mistakes in TTP are referred to as “laboratory errors”, but are actually due to poor communication, actions taken by others involved in the testing process (physicians/clinicians, nurses and phlebotomists) or poorly designed processes which are outside the laboratory’s control (Plebani and Bonini 2002). Likewise, there is evidence that laboratory information is only partially utilised: a recent report demonstrates that 45% of the results for urgent laboratory tests requested by A & E department of one hospital were never accessed, or were accessed far too late (Kilpatrick and Holding 2001). In the modern approach to total quality management in clinical laboratory, which is centred on patient’s needs and satisfaction, the risk of

errors and mistakes in pre-and post-examination steps must be minimised in order to guarantee total quality of laboratory services.

1. 11.

a) adapted From: The total testing process applied to therapeutic drug monitoring.

Therapeutic Drug Monitoring,47-82 (Barr and Schumacher 1995).

Today, many clinical laboratories still operate according to the traditional laboratory model, the old laboratory model (Figure 1.2), which is a linear, unidirectional flow process of one activity preceding the next activity. The traditional (current) clinical microbiology laboratory is isolated from what tests are ordered (input) and how their results are interpreted (output). The traditional laboratory cycle operates in one direction. The major concern in this model is the quality of test performance and the

Patient Care

production features and internal organisation of the laboratory (analytical phase). In the traditional model, the focus is on the science and technology and quality of test performance, and communication is almost non existent prior to the test request, or after the result is released. In this model, the clinical laboratory is not concerned with clinical appropriateness or interpretation of test results (Barr 1999).

Figure 1.2: The traditional laboratory cycle

The new laboratory model (Figure 1.3) is an interactive process, and the scope of laboratory services is broader. In the interactive clinical microbiology laboratory cycle, laboratory scientists and clinicians interact to improve how tests are ordered, how tests are performed, and how results are interpreted. The interactive laboratory cycle operates both directions. In this model, the focus is not only on the quality of test data generated (process/analytical), but also on the clinical appropriateness of test requests (input/preanlytical) and the correct interpretation of and response to laboratory information (output/postanalytical). The laboratory’s involvement in the entire total testing process will have a positive impact on patient outcomes, improve the clinical relevance and value of the laboratory’s service, and greatly enhance the cost-effectiveness of the laboratory operation (Barr 1999).

To demonstrate how appropriate test utilisation will promote a better integration of laboratory services into the patient care process. This was described by Barr, and is known as Barr’s model of laboratory utilisation (Barr 1999). This model identifies the factors that affect the clinician’s decisions or actions at each step of the laboratory utilisation process.

Test Ordered INPUT

Test Performed PROCESS

Test Interpreted OUTPUT

Figure 1.3: The New Interactive Laboratory Cycle

According to Barr’s model, in the input phase (pre-analytical), one must question if the test is appropriate for the stage of the clinical condition and if the time of specimen collection is correct. During the process phase (analytical), one must determine if, within clinically relevant guidelines, the test result is accurate and precise and timely with respect to the TAT needs of physicians. Finally, in the output phase (post-analytical), one must evaluate if the results are properly interpreted and integrated into patient care or if data overload is confusing or misleading physicians (Barr 1999).

Barr’s model also demonstrated any appropriate roles for the laboratory scientist at each step of this process. Starting with the clinician’s assessment of the patient’s condition, the laboratory utilisation process moves to laboratory testing phases, which result in the application and integration of the test results into patient care. All three phases are critical. If a test is clinically indicated, or the laboratory’s precision is beyond that needed for clinical judgements, or if the result is misinterpreted, then an accurate and precise laboratory result is of no value.